China’s imports from North Korea plunged 92.6 per cent in June compared with a year earlier under United Nations sanctions imposed to stop Pyongyang’s nuclear and missile programmes, the customs agency said on Friday.

Exports of Chinese oil and other goods to the North fell 40.6 per cent, a customs agency spokesman, Huang Songping, said. He gave no financial totals.

The trade curbs have remained in place despite diplomatic contacts including US President Donald Trump’s June meeting with North Korean leader Kim Jong-un.

American Secretary of State Mike Pompeo, who visited Pyongyang this month, said sanctions would not be lifted until Kim followed through on his pledge to scrap its nuclear weapons.

China provides nearly all of the isolated North’s trade and energy supplies. Beijing has imposed limits on oil exports and sharply reduced North Korean revenue by banning purchases of its textiles, seafood and coal.

Beijing was long Pyongyang’s diplomatic protector but has supported the UN sanctions out of frustration at what Chinese leaders see as their neighbour’s increasingly reckless behaviour.

Beijing also ordered North Korean-owned restaurants and other businesses in China, an important revenue source, to close.

In the first six months of the year, Chinese imports fell 88.7 per cent from the same period of 2017 to 690 million yuan (US$103 million), according to Huang. Exports declined 43.1 per cent to 6.4 billion yuan.

Huang said Chinese exports to the North had fallen for 11 straight months, while imports had declined for 10 months.

Also on Friday, a deputy Chinese foreign minister sounded a reassuring note about North Korea after Trump complained Beijing might be disrupting diplomatic efforts due to its trade dispute with Washington.

The official, Kong Xuanyou, said there had been “positive momentum” and Beijing was in “close coordination” with Washington.

“We will stay in touch with the United States through various channels in a joint effort to uphold peace and stability on the peninsula to facilitate the political settlement of the Korean issue,” Kong said.

If the governments involved “candid discussions as equals”, then “all the questions will find the right answers”, he said.

Relations between China and North Korea have improved with Kim visiting China three times.

In two of the visits, officials from two nations have discussed economic cooperation. Kim also visited border cities with China.

He visited a cosmetics factory in the Sinuiju special economic zone, across the Yalu River from China’s port city Dandong, North Korea’s state media reported earlier this month.

He was accompanied to Samjiyon by senior North Korean officials, including former Korean People’s Army vice-marshal Hwang Pyong-so and Jo Yong-won, from the Organisation and Guidance Department of the Workers’ Party of Korea.